/**
 * Partition the canonical file set across shards by longest-matching root dir.
 *
 * Phase 1 of graph-sharded-exact-parity. The sharded engine used to RE-DERIVE
 * each shard's files from that package's own tsconfig — which excludes the
 * package's `__fixtures__` tree AND (for some packages) its test files — so it
 * silently dropped files the exact engine kept. The fix: enumerate the project
 * once (root discovery → {@link resolveCanonicalFileSet}), then ASSIGN each
 * canonical file to a shard here. Discovery now only supplies shard BOUNDARIES
 * (rootDir + configPath), never the file set.
 *
 * Assignment rule: each file goes to the unit whose `rootDir` is its LONGEST
 * matching path prefix (so a file under `packages/foo/src/...` lands in the
 * `foo` unit, not a shorter-prefix ancestor unit). Files under NO unit's
 * rootDir — root scripts, `.config`, files in packages without a tsconfig —
 * fall into a synthetic ROOT shard anchored at the project root + root tsconfig.
 *
 * Invariant (asserted by callers' tests): `union(shard.files) === canonicalFiles`
 * and every file lands in EXACTLY one shard — the partition is total and
 * disjoint, which is what makes the merged sharded catalog equal the exact one.
 */
import type { Shard } from './shard-model.js';
/** Stable id of the synthetic catch-all shard that owns files under no unit. */
export declare const ROOT_SHARD_ID = ":root";
/** A shard boundary derived from discovery: where a unit lives + its config anchor. */
export interface ShardBoundary {
    /** Stable unit id (e.g. `pkg:core`). MUST NOT be {@link ROOT_SHARD_ID}. */
    readonly id: string;
    /** Absolute root dir the unit's files live under. */
    readonly rootDir: string;
    /** Absolute config anchor (tsconfig.json) for the unit, if any. */
    readonly configPathAbs?: string;
}
/** Inputs to {@link partitionFilesIntoShards}. */
export interface PartitionInput {
    /** The canonical (fixture-excluded) project-wide file set — absolute paths. */
    readonly canonicalFiles: readonly string[];
    /** Unit boundaries from discovery (rootDir + config anchor). */
    readonly units: readonly ShardBoundary[];
    /** Absolute project root — the synthetic root shard's rootDir. */
    readonly projectRoot: string;
    /** Absolute root config anchor (root tsconfig.json), threaded onto the root shard. */
    readonly rootConfigPathAbs?: string;
}
/**
 * Assign each canonical file to the unit whose rootDir is its longest matching
 * prefix; files under no unit go to a synthetic ROOT shard. Returns only
 * non-empty shards. Deterministic: shard order follows the input unit order
 * (root shard last); each shard's files preserve canonical input order.
 */
export declare function partitionFilesIntoShards(input: PartitionInput): Shard[];
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